Hus:
Congratulations on owning the Electromag Pracbox and thank you for your purchase. I’m Hus and in this video, I will give you a bit of induction on how to use the Electromag Pracbox, including product and user safety. This will also help you get the most out of the product. We will discuss each part or a group of parts and discuss what they are, how to use them, what can go wrong with them, and how to avoid that. We will cover these components in this video. Let’s get started.

Open relay. This is an open relay with a 12 volt coil and 40 amp single pole double throw contacts. Red is the positive terminal of the coil and black is negative. The yellow terminal is common, the top white terminal is normally open contact, and the bottom white terminal is normally close contact. You can use this relay to show how they can be used to control higher voltage loads via a low voltage circuit. There is a direction protection diode installed for the coil so that the incorrect polarity will blow the fuse. Please follow the correct circuit connections to avoid any downtime.

Contactor. We have installed a 24 volt contactor with three pole plus one normally open contact with the ratings of 9 amps. Red is the positive terminal of the coil and black is negative. The white terminals are contacts for the three poles, and the yellow terminals are contacts for the normally open. You can use this contact to explain its workings and how multiple circuits may be controlled using one contact. There is a direction protection diode installed for this coil so that the incorrect polarity will blow the fuse. Please follow the correct circuit connections to avoid any downtime.

DPDT relay. This is a double pole double throw relay with 24 volt coil and 12 amp contacts. Red is the positive terminal of the coil and black is negative. The blue terminals are common for each contact. Yellow terminals are normally closed and the white terminals are normally open. You can use this relay to show the differences and similarities between relays and contactors. There is a direction protection diode installed for this coil so that the incorrect polarity will blow the fuse. Please follow the correct circuit connections to avoid any downtime.

Interface relay. There is an interface relay installed in the Electromag Pracbox with a 12 volt coil and 6 amp single pole normally open contact. Red is the positive terminal of the coil and black is negative. The white terminals are the normally open contact terminals. This type of relays don’t require a lot of current to energize and that’s why they are used to power big contactors through more sensitive electronics like PLCs and sensor outputs. There is a direction protection diode installed for this coil so that the incorrect polarity will blow the fuse. Please follow the correct circuit connections to avoid any downtime.

Push buttons. There are three momentary push buttons in the Electromag Pracbox, each of which have one normally open and one normally closed contacts rated at 5 amps. The white terminals are for normally closed contacts and the yellow terminals are for normally open. You can use these to teach basic logic and motor control circuits.

Coils and core. In each Electromag Pracbox, you will get two coils, one with 200 turns and the other with 400 turns. You will also get a core as an accessory to go with these coils. 200 turns coil has a blue case and maximum current rating of 2 amps. 400 turns coil has a yellow case and maximum current rating of 1 amp. You can use these coils to show the effect of the number of turns and the core on magnetic field strength. Do not exceed the maximum rated current, otherwise the coils may burn.

Reed switches. There are two reed switches in this Pracbox, one cylindrical type and the other is glass type. Both of them are normally open and have the switching current rating of 1 amp. You can show the activation of the contacts of these reed switches when a magnet is brought close to them. Do not exceed the rated current or leave a strong magnet in their vicinity for too long. In both cases, the contacts could stay closed.

Power supplies. The Electromag Pracbox has two variable power supplies that are capable of supplying up to 25 volts at 2.5 amps each. The switches in these power supplies are wired in a way that the current will only flow when the switch is in the on position, but you can set the voltage even when the switch is off. You can use these to show the working of almost all the components in this Pracbox. For example, use 12 volts from one power supply to power the open relay and 24 volts to power the motor through this relay. The current in this supply is limited to 2.5 amps, so even short-circuiting the supply will not cause any problems except a blown fuse. However, we advise against dead shorts to avoid downtime. There are 2 amp fast blow M205 fuses installed for the circuit protection.

SPDT toggle switch. This is a single pole double throw switch with the current rating of 5 amps. The yellow terminal is wired to the common of the switch and the red terminals on either side are connected to terminals one and two. You can use this switch to show the difference between momentary push buttons and latching switches, and also to show the benefits of a holding circuit as compared to a latching circuit. Do not connect the power supply across the switch to avoid a dead short.

Proximity switches. There are two proximity switches in the Electromag Pracbox. The small one is a 24 volt NPN hall-effect proximity switch, and the bigger one is a 24 volt PNP inductive proximity switch. The red terminals for bolt switches are positive and the supply voltage can range from 12 volts to 24 volts. The blue terminals are the negative of the proxies and the black terminals are the outputs. For NPN, after connecting the supply terminals, connect its red terminal to the red terminal of the LED lamp and the black terminal of the NPN switch to the black terminal of the lamp. This is a syncing circuit connection. For PNP, after connecting the supply terminals, connect its black terminal to the red terminal of the LED lamp and the blue terminal of the PNP switch to the black terminal of the lamp. This is a sourcing circuit connection. The outputs of the proxy switches provide very low currents and connecting them to high current or inductive loads like relay coils or motors can damage them. So please use them with LED lamps or the interface relay.

Inductor. This is a 100 millihenry common mode inductor with a maximum current rating of 300 milliamps. The two white terminals on one side of the inductor are connected to the ends of one winding, and the two yellow terminals on the other side are connected to the ends of the other winding. You can use either sides to demonstrate the magnetic field that the inductor generates when current passes through it. Do not increase the maximum rated current to avoid damage to the coils.

50 watt potentiometer. This is a 50 watt potentiometer or a variable resistor with the maximum resistance of 50 ohms. The dial is an indication only and is not to be used as the value of the resistance. The yellow terminal is the common and the white terminals on either side are the opposite ends of the resistance wire. As you turn the dial from zero to 100, the resistance between the yellow and the left white terminal will increase, and at the same time the resistance between the yellow and the right white terminal will decrease. You can use this to control the current to the permanent magnet motor to affect its speed and torque or use it as a load for the generator. The current across the potentiometer can increase to higher levels and heat the winding up if the resistance is set to a very low value or zero. To avoid the situation, start with the dial at the mid-range and never drop the resistance to a very low value or zero when used as a load for the generator.

LED lamps. There are two 24 volt LED lamps installed in this Pracbox, red and green. They work well with AC or DC, so the polarity doesn’t matter. You can use them as indicators for the proxy switches or as Pilot lamps.

Batten holders. These are B22 style batten holders, and you will also get two 24 volt 25 watt lamps as separate accessories with this Pracbox. You can use these lamps as resistive loads for the generator output or operate them via relays and contactor. Since the lamps are resistive, they will get hot after a few minutes. Please only touch them after they have cooled down.

Motors. The Electromag Pracbox has two 24 volt, 3,600 RPM permanent magnet DC motors. They are coupled with a timing belt, which means when you connect one of them to the power supply, the other one will become a generator. Besides using them as a motor and generator set, you can also use just one motor in a stop-start circuit through the relays or contactor. Rotating equipment pose an obvious hazard and the users should avoid touching the rotating paths and restrict loose clothing and hair. Another thing to avoid without proper understanding is powering both motors at the same time.

Power entry fuse. At the back of the Pracbox, there is a power entry module that has a 2 amp fast blow M205 fuse for circuit protection. In case of a blown fuse, always replaced with a fuse of appropriate type and rating.

We have covered all the aspects of the Electromag Pracbox, and you now have enough information to ensure the safety of the product and the users. We are always here for you. If you have any questions or run into problems, please feel free to contact us. We hope you and your learners enjoy using the Electromag Pracbox. Thanks for watching.